Acoustic barriers based on periodic arrays of scatterers

Abstract

It is well known that certain periodic structures built by repetition of elements produce sound attenuation effects as a consequence of the destructive interference of the scattered waves by these elements. The sound attenuation results that we got from transmission experiments with these kind of structures, so-called sonic crystals (SCs), led us to think that SCs could be used as an acoustic barrier. Until now, most of the transmission experiments with these periodic arrays of scatterers have been performed under controlled conditions, so how they would behave outdoors is still not well known. In this letter we present outdoor-experimental results for two-dimensional SCs and from these it can be concluded that periodic arrays of scatterers are a suitable device to reduce noise in free-field conditions.

Optimum control of broadband noise by arrays of cylindrical units made of a recycled material

“…Since the late nineties, two-dimensional sonic crystals were proposed [3,4,5,6,7] as an alternative to conventional noise barriers. Sonic crystals consist of periodic arrangements of scatterers that inhibit sound transmission for certain ranges of frequencies called bandgaps, as photonic crystals do with light.…”

Numerical Evaluation of Sound Attenuation Provided by Periodic Structures

“…In the first group, aspects such as the influence of so called point defects (Wu et al, 2009) or the existence of waveguides in which the sound propagates with low attenuation (Vasseur et al, 2008) can be mentioned. In the field of the practical uses of sonic crystals, one which may be regarded perhaps as the most promising is their precise use for the selective attenuation of sound, for example as traffic noise barriers (Sánchez-Pérez et al, 2002). A very recent work on this topic (Castiñeira-Ibáñez et al, 2012) has addressed the classification of sonic crystal barriers in terms of relevant European standards for the determination of the intrinsic characteristics of acoustic barriers.…”

Use of dual planar jets for the reduction of flow-induced noise

“…[1][2][3][4][5][6] In particular, airframe noise, which is generated through the interaction between the turbulent flow and the solid bodies on the aircraft, has been identified as an "aircraft noise barrier" since the early seventies. 7 Therefore, considering the interdisciplinary challenge between fluid mechanics and acoustics arising from this noise effect, airframe noise reduction has become a major concern for stakeholders within the aviation sector, acoustic experts, fluid mechanics engineers and researchers.…”